Dr Srujana Sahebjada
People with keratoconus have thicker fovea and maculae than those without the disease, the Australian Study of Keratoconus has found for the first time. It identified, also for the first time, that asthma appears to be a risk factor for keratoconus.
Research optometrist Dr Srujana Sahebjada said findings could have practical implications for optometrists as a thicker macula could be the first sign of sub-clinical keratoconus, before changes in corneal thickness appeared in clinical disease.
Dr Sahebjada, from the Ocular Genetics Unit at the Centre for Eye Research Australia, is the lead researcher of the study. She found that the changes appeared in early keratoconus.
‘In future, optometrists may be able to do retinal and corneal imaging in members of keratoconus families not diagnosed with the disease and this may provide a possible diagnostic test before it is clinically apparent, allowing treatment options at earliest possible stages,’ she said.
‘Having thicker maculae could be a general disorganisation of the eye in keratoconus patients and my hypothesis is that it is the posterior segment trying to compensate for changes in the anterior segment.
‘I am planning follow up OCTs to see if the increase in macular thickness corresponds with the corneal curvature.’
Dr Sahebjada is now recruiting families of patients, including siblings and children.
She said more children were being diagnosed with keratoconus, possibly due to prevalence increasing, increased awareness and optometrists having the latest technology. Parents are also aware of genetic links and that early diagnosis in their children could open the way to treatments including corneal cross-linking to delay progression.
The macula findings are under review for publication in a journal and she has also submitted the asthma findings to a journal.
Dr Sahebjada recruited the first 300 people for the study from the Royal Victorian Eye and Ear Hospital, Eye Surgery Associates, and Richard Lindsay and Associates.
Analysis of risk factors found that those with severe keratoconus were more likely to have asthma than patients with less severe forms of keratoconus.
‘This could be because of allergic pathways—the two conditions could be related,’ Dr Sahebjada said. ‘Previous research suggested there could be a link but this is the first study to show a strong link.’
The study also found that worse vision in the patient’s better eye was associated with reduced vision and quality of life.
Dr Sahebjada said there was a higher prevalence of the disease in Asian people but the study had identified two keratoconus genes in Australia’s Caucasian population, findings which were published this year and confirm that some keratoconus has a genetic basis.
One is the hepatocyte growth factor gene, an important signalling gene, and another is a corneal thickness gene. This finding is also supported by her assessment of anterior segment parameters where corneal thickness was found to be an important marker for detecting subclinical keratoconus at different levels of disease severity.
The study has involved patients mainly from Victoria with some from Sydney and Adelaide but is now extending nationwide and is tapping into Keratoconus Australia’s database to recruit more patients.
Patients fill in online questionnaires, their optometrists provide clinical data and patients who cannot provide a blood sample in Victoria send DNA via saliva tubes through the mail.
Optometrists with keratoconus patients or families interested in taking part can email email@example.com.